1. Field of the Invention
The present invention relates to a condenser condensing steam into condensate with cooling water.
2. Description of the Related Art
A condenser applied to, for example, a nuclear power plant or a thermal power plant, condenses turbine exhaust steam which has ended an expansion work by steam turbine, into condensate, with cooling water. The cooling water used in such a condenser is sea water or fresh water from a cooling tower. The cooling water is made to flow in a heat-transfer pipe arranged in the condenser to exchange heat with the exhaust steam introduced into the condenser and condense the turbine exhaust steam.
One of the types of condenser is a multistage pressure condenser which comprises a plurality of, i.e. two or three main body shells (i.e. a plurality of condensers) and in which pipes are serially arranged such that the cooling water pass through each of the main body shells at a plurality of times. In the main body shell of the multistage pressure condenser which is arranged on a slip stream side of the flow path of the cooling water, vacuum in the main body shell becomes lower due to rise of cooling water temperature. For this reason, the pressure of the turbine exhaust steam introduced into the main body shell arranged at the slip stream side of the flow path of the cooling water becomes higher.
Temperature of the condensate condensed in the condenser becomes a saturation temperature which substantially corresponds to the turbine exhaust pressure introduced into the main body shell of the condenser. Thus, in the multistage pressure condenser in which the main body shells are different in pressure, condensate temperatures of the multistage pressure condenser having, for example, three types of pressures in the main body shells are higher in order of a high pressure condenser, an intermediate pressure condenser and a low pressure condenser.
Since the condensate generated in the condenser is supplied again to the system as feed water, a higher temperature of the condensate is desirable in terms of heat efficiency. In the above-described three-shell multistage pressure condenser, it is preferable to make the condensate of a comparatively low temperature generated in the intermediate pressure condenser and the low pressure condenser close to the condensate temperature in the high pressure condenser.
FIG. 4A is a front sectional view showing a structure of a conventional multistage condenser 100. FIG. 4B is a side sectional view showing the structure of the conventional multistage condenser 100.
The multistage condenser 100 is constituted by connecting a high pressure condenser 1, an intermediate pressure condenser 2 and a low pressure condenser 3 which are different in inner pressure, serially in this order.
The high pressure condenser 1 has a high pressure turbine 81 mounted on a head side, and a high pressure cooling tube bank 8 constituted by a number of heat-transfer pipes is provided inside the condenser. At a bottom portion of the high pressure condenser 1, a high pressure hot well 6 is provided and a condensate outlet box 7 is also provided at a lower side.
The high pressure hot well 6 consists of a liquid phase part 6a serving as the bottom portion where the condensate is stored, and a vapor phase part 6b provided between the liquid phase part 6a and the high pressure cooling tube bank 8. In addition, a heater drain tube 13 is connected to the high pressure condenser 1 and a high pressure baffle 9 is provided at the connection part.
The intermediate pressure condenser 2 has a lower inner pressure than the high pressure condenser 1, and has an intermediate pressure turbine 82 mounted on a head side. An intermediate pressure cooling tube bank 28 constituted by a number of heat-transfer pipes is provided inside the condenser, similarly to the high pressure condenser 1. A reheat chamber 22 partitioned by a pressure shroud 4 is provided at a lower portion of the intermediate pressure cooling tube bank 28.
In the reheat chamber 22, a steam duct 10 serving as high pressure steam introducing means, connected to the high pressure condenser 1, is provided. At a bottom portion of the intermediate pressure condenser 2, an intermediate pressure hot well 26 is provided. The intermediate pressure hot well 26 consists of a liquid phase part 26a serving as a bottom portion where the condensate is stored, and a vapor phase part 26b provided above the liquid phase part 26a. The vapor phase part 26b is the reheat chamber 22. The liquid phase part 6a of the high pressure hot well 6 and the liquid phase part 26a of the intermediate pressure hot well 26 communicate with each other by a condensate tube 11.
The low pressure condenser 3 has a lower inner pressure than the intermediate pressure condenser 2, and has a low pressure turbine 83 mounted on a head side. A low pressure cooling tube bank 38 constituted by a number of heat-transfer pipes is provided inside the condenser, similarly to the high pressure condenser 1 and the intermediate pressure condenser 2. A reheat chamber 23 partitioned by a pressure shroud 5 is provided at a lower portion of the low pressure cooling tube bank 38.
In the reheat chamber 23, a steam duct 30 serving as high pressure steam introducing means is provided and connected to the reheat chamber 22 of the intermediate pressure condenser 2. At a bottom portion of the low pressure condenser 3, a low pressure hot well 36 is provided. The low pressure hot well 36 consists of a liquid phase part 36a serving as a bottom portion where the condensate is stored, and a vapor phase part 36b provided above the liquid phase part 36a. The vapor phase part 36b is the reheat chamber 23. The liquid phase part 26a of the intermediate pressure hot well 26 and the liquid phase part 36a of the low pressure hot well 36 communicate with each other by a condensate tube 31. Furthermore, the heater drain tube 13 is connected to the low pressure condenser 3, and a low pressure baffle 39 is provided at the connection part.
As cooling water, for example, sea water is introduced into each of the high pressure cooling tube bank 8, the intermediate pressure cooling tube bank 28 and the low pressure cooling tube bank 38. In the multistage pressure condenser, the high pressure cooling tube bank 8, the intermediate pressure cooling tube bank 28 and the low pressure cooling tube bank 38 are connected serially. The cooling water is first introduced into the low pressure cooling tube bank 38, passes through the intermediate pressure cooling tube bank 28 after passing through the low pressure cooling tube bank 38, and is finally introduced intro high pressure cooling tube bank 8 and discharged.
In the high pressure cooling tube bank 8, the high pressure turbine exhaust which finishes the work at the high pressure turbine 81 and is supplied to the high pressure condenser 1 is condensed as a high pressure condensate by exchanging heat via the heat-transfer pipes with the cooling water of the highest temperature introduced into the high pressure cooling tube bank 8, and is recovered in the liquid phase part 6a of the high pressure hot well 6 of the high pressure condenser 1.
In the intermediate pressure cooling tube bank 28, the intermediate pressure turbine exhaust which finishes the work at the intermediate pressure turbine 82 and is supplied to the intermediate pressure condenser 2 is condensed as an intermediate pressure condensate by exchanging heat via the heat-transfer pipes with the cooling water passing through the intermediate pressure cooling tube bank 28. The intermediate pressure condensate is temporarily stored on the pressure shroud 4 of the intermediate pressure condenser 2 and then sprayed into the reheat chamber 22 through a number of circle holes formed on a perforated panel provided on the pressure shroud 4. The high pressure steam is introduced into the reheat chamber 22 from the vapor phase part 6b of the high pressure hot well 6 provided in the high pressure condenser 1 via the steam duct 10. The intermediate pressure condensate sprayed into the reheat chamber 22 by the high pressure steam is directly reheated by the heat exchange. The reheated intermediate condensate is finally stored in the liquid phase part 26a of the intermediate pressure hot well 26, supplied to the liquid phase part 6a of the high pressure hot well 6 via the condensate tube 11, and supplied to a feed water heater (not shown) through a condensate outlet box 7.
In the low pressure cooling tube bank 38, the low pressure turbine exhaust which finishes the work at the low pressure turbine 83 and is supplied to the low pressure condenser 3 is condensed as a low pressure condensate by exchanging heat via the heat-transfer pipes with the cooling water of the lowest temperature passing through the low pressure cooling tube bank 38. The low pressure condensate is temporarily stored on the pressure shroud 5 of the low pressure condenser 3 and then sprayed into the reheat chamber 23 through a number of circle holes formed on a perforated panel provided on the pressure shroud 5. The high pressure steam in the vapor phase part 6b of the high pressure hot well 6 is further introduced into the reheat chamber 23 from the reheat chamber 22 serving as the vapor phase part 26b of the intermediate pressure hot well 26 via the steam duct 30. The low pressure condensate sprayed into the reheat chamber 23 by the high pressure steam is directly reheated by the heat exchange. The reheated low condensate is finally stored in the liquid phase part 36a of the low pressure hot well 36, supplied to the liquid phase part 6a of the high pressure hot well 6 via the condensate tube 31, the liquid phase part 26a of the intermediate pressure hot well 26 and the condensate tube 11, and supplied to a feed water heater (not shown) through the condensate outlet box 7.
A heater drain generated by condensing in the feed water heater bleed steam of the steam turbine for reheating the feed water flows into the heater drain tube 13. The flowing heater drain, which is recovered in the high pressure condenser 1 or the low pressure condenser 3, collides with the high pressure baffle 9 or the low pressure baffle 39, reduces the flow force and falls into the liquid phase part 6a of the high pressure hot well 6 or the liquid phase part 36a of the low pressure hot well 36.
As for a known condenser, for example, Jpn. Pat. Appln. KOKAI Publication No. 11-173768, Jpn. U.M. Appln. KOKOKU Publication No. 49-12482, Japanese Patent No. 3706571, Jpn. Pat. Appln. KOKAI Publication No. 49-032002 and the like should be referred to.